Physics: Forces and Motion

Force and Motion

Definition of Force

• A push or pull that causes an object to change its motion or shape
• Measured in Newtons (N)
• Can be either external or internal

Types of Forces

• Gravity: the force of attraction between two objects with mass
• Friction: the force that opposes motion between two surfaces in contact
• Normal Force: the force exerted by a surface on an object that is in contact with it
• Tension: the force exerted by a stretched string or wire
• Air Resistance: the force that opposes the motion of an object through the air

Newton's Laws of Motion

First Law (Law of Inertia)

• An object at rest will remain at rest, and an object in motion will continue to move with a constant velocity, unless acted upon by an external force
• Inertia: the tendency of an object to resist changes in its motion

Second Law (F = ma)

• The force applied to an object is equal to the mass of the object multiplied by its acceleration
• F = ma (force = mass x acceleration)

Third Law (Action and Reaction)

• For every action, there is an equal and opposite reaction
• When one object exerts a force on another object, the second object always exerts an equal and opposite force on the first object

Motion

• Displacement: the change in position of an object from its initial to its final position
• Distance: the total length of the path traveled by an object
• Velocity: the rate of change of an object's position with respect to time
• Acceleration: the rate of change of an object's velocity
• Speed: the magnitude of an object's velocity (scalar quantity)

Force and Motion

Definition of Force

• Force is a push or pull that causes an object to change its motion or shape, measured in Newtons (N).
• Force can be either external or internal.

Types of Forces

• Gravity: a force of attraction between two objects with mass.
• Friction: a force that opposes motion between two surfaces in contact.
• Normal Force: a force exerted by a surface on an object that is in contact with it.
• Tension: a force exerted by a stretched string or wire.
• Air Resistance: a force that opposes the motion of an object through the air.

Newton's Laws of Motion

First Law (Law of Inertia)

• An object at rest will remain at rest, and an object in motion will continue to move with a constant velocity, unless acted upon by an external force.
• Inertia is the tendency of an object to resist changes in its motion.

Second Law (F = ma)

• Force (F) is equal to the mass (m) of an object multiplied by its acceleration (a): F = ma.
• The unit of force is the Newton (N), which is equal to kg·m/s².

Third Law (Action and Reaction)

• For every action, there is an equal and opposite reaction.
• When one object exerts a force on another object, the second object always exerts an equal and opposite force on the first object.

Motion

• Displacement: the change in position of an object from its initial to its final position.
• Distance: the total length of the path traveled by an object.
• Velocity: the rate of change of an object's position with respect to time, measured in meters per second (m/s).
• Acceleration: the rate of change of an object's velocity, measured in meters per second squared (m/s²).
• Speed: the magnitude of an object's velocity, measured in meters per second (m/s).